The invention relates to a tone generator with a semiconductor circuit for the automatic generation of a tone sequence including at least two different tones, by means of an electro-acoustic transducer or loudspeaker driven by the semiconductor circuit, the semiconductor circuit containing an RC-oscillator and at least one frequency divider driven by the oscillator.
Semiconductor circuits for the driving of electro-acoustic transducers, i.e. loudspeakers, have been available for some time. In such circuits electrical oscillations corresponding to the tones to be produced are generated in the semiconductor circuit on a purely electrical basis, especially on a digital basis. These oscillators are then supplied to the loudspeaker in order to generate the tones corresponding to the frequency of the respective electrical oscillations with its help. One example of this is electric organs which, however, are manually operated and contain rather sophisticated circuitry. It is desired to monolithically integrate the circuit components performing the various functions to the greatest possible extent, because external circuit components weigh heavily costwise.
A tone generator of this type is described in the German patent application DE-AS No. 26 01 1922.
Besides electronic musical instruments, there is also a simpler apparatus for tone generation on the basis of monolithically integrated semiconductor circuits. One example of this is electronic signal generators which, upon the actuation of a push button, generate a given melodic tone sequence, such as a common chord, without further interference. Examples are described in "Funkschau" (1980) No. 20, pages 87-90. Since, in contrast to the electronic musical instruments, the tone sequence is fixed in these cases, such a circuit can be constructed in a much simpler manner. However, electrical gongs, such as for use as a bell substitute, usually involve merely using the square-wave oscillations furnished by an RC-oscillator and corresponding frequencywise, for instance, to the highest tone of the sequence for the derivation of the electrical oscillations corresponding to the other tones of the tone sequence to be produced. Therefore, only one electrical oscillation is available for each of the individual tones of the tone sequence, which are then supplied to the loudspeaker in accordance with the tone sequence.